Amphisphaeriales » Sporocadaceae » Seimatosporium

Seimatosporium rosigenum

Seimatosporium rosigenum Goonas., Camporesi, & K.D. Hyde, in Wanasinghe et al., Fungal Diversity: 10.1007/s13225-018-0395-7, [193] (2018)

Index Fungorum number: IF 554223; Facesofungi number: FoF 04066

Etymology: The specific epithet reflects the host genus Rosa.

Holotype: MFLU 15-0782.

Saprobic on spines of Rosa canina. Sexual morph: Undetermined. Asexual morph: Conidiomata pycnidial, solitary to gregarious, immersed to semi-immersed, unilocular, subglobose, up to 390–420 μm diam, 120–130 μm high, brown to black. Conidiomata wall composed of thin-walled, outer, brown cells of textura prismatica and inner, pale brown cells of textura angularis, up to 10 μm thick. Conidiophores arising from the inner cells of the basal cell layers, hyaline, unbranched, smooth, up to 10 μm long. Conidiogenous cells enteroblastic, phialidic, cylindrical to doliiform, discrete, hyaline, smooth. Conidia (8.5–)10–14 × 3.5–5.5 μm (x̄ = 11.7 × 4.7 μm, n = 30), brown to olivaceous, fusiform, straight, 3-septate, septa darker than the rest, basal cell conic with obtuse base, pale brown to brown, 2.2–3 μm long (x̄ = 2.6 μm), two median cells doliiform, with thick verruculose walls, occasionally constricted at the septa, concolourous, together 4.5–8 μm long (x̄ = 6.2 μm), second cell from base 2.5–4 μm (x̄ = 3 μm); third cell 2–4 μm (x̄ = 3 μm); apical cell hyaline, conical, 1.2–3.2 μm long (x̄ = 2.4 μm), with 1 tubular apical appendage, unbranched, arising not centrally but near the apex of the apical cell, 16–25 μm long (x̄ = 16.2 μm); basal appendage mostly absent.

Culture characteristics: Colonies on PDA reaching 2 cm diam. after 7 days at 16–18 °C, circular, umbonate, fluffy, with undulate margins, colony from above grey, pale yellow at the center; reverse grey.

Material examined: ITALY, Province of Pesaro-Urbino [PU], Monte Nerone, on dead aerial spines of Rosa canina L. (Rosaceae), 11 June 2012, Erio Camporesi IT 430 (MFLU 15-0782, holotype), ibid. (MFLU 15-0783, MFLU 15-0784, MFLU 15-0785, paratypes), living culture, MFLUCC 15-0563 = KUMCC 16-0112.

GenBank: ITS: MG828960, LSU: MG829071

Notes: Seimatosporium rosigenum shares certain morphological similarities with S. lichenicola, S. rosae, S. rosarum and S. salicinum, which have also been reported on Rosa spp. (Nag Raj 1993, Farr and Rossman 2017). However, they can be distinguished from our new species based on the number of septa and presence or absence of appendages. While S. rosigenum has 3-septate conidia with mostly apical appendages, S. salicinum has 2–3 septate conidia with both apical and basal appendages. The conidia of S. rosae and S. rosarum have either 2–3 septa with only basal appendages (Nag Raj 1993). In our molecular phylogeny our new species groups with S. lichenicola, but can be differentiated in having comparatively wider (13–15 × 5.5–6.5 μm vs. 10–14 × 3.5–5.5 μm of S. rosigenum) conidia lacking appendages (Sutton 1980).